by Jeff Zillgitt, USA TODAY Sports

"It always a question. You never know until it's over," Bosh said. "Question is healthy, because it's a healthy amount of fear that you have to have.

"Not knowing is the best medicine."

Never before since the formation of the Big 3 - Bosh, LeBron James and Dwyane Wade - in 2010-11 has the playoff future been so unknown at the start of the postseason.

The two-time defending champs are trying to win their third consecutive NBA championship and reach the Finals for the fourth consecutive season. The Los Angeles Lakers (2000-02) are the last team to win three consecutive titles, and the Boston Celtics (1984-87) are the last team to reach the finals four consecutive times, winning the title in 1984 and 1986.

Miami begins the postseason against the Charlotte Bobcats, who have not beaten the Heat in 15 games since the triumvirate formed. Charlotte forced overtime in one game and lost by one point in another this season.

The weight of that title pursuit gets heavier and heavier.

"It's extremely difficult. It's supposed to be. That's why not many have done it before," Bosh said. "I hope we can meet every challenge, fight through these barriers and get better and win it.

The season has been a grind, but James said, "I always feel taxed at this point of the season. I work the game. I put a lot of energy and effort into the game. I do it at a high pace every night, and who wouldn't be tired or taxed at this point unless you play for the Spurs."

The Heat operate under the idea that nothing is guaranteed, and that is especially true this season. Miami meandered through the regular season, finished second behind the Indiana Pacers in the East and heads into the playoffs more vulnerable than in any of the previous three seasons.

And of course, the playoffs will play out in front of a large backdrop and another unknown for the Heat: Will Bosh, James and Wade be with Miami next season?

First thing's first: the playoffs.

"You want to play well and you want to feel good about your game going into the postseason," Heat coach Erik Spoelstra said. "That's what it's always been with us. ... Can we get this thing to another level? We still have time to do it. It just takes a game (snaps fingers) for things to change."

Beginning March 1, Miami finished the season 13-14, and most concerning to Spoelstra and the Heat were several games in that stretch in which Miami either had the lead or was tied in the fourth quarter and lost.

"Typically, we have great confidence in being able to close out games regardless of the circumstances. No excuses - who's in, who's out, back-to-backs, schedule, lots of games - what we're talking about is let's improve in this area and let's find a way. ... That's one of our biggest challenges right now."

The biggest reason for Miami's inability to close out games is their constant lineup changes because of injury and Spoelstra's decision to find players who can contribute using a revolving door off the bench.

Wade missed 28 games this season as part of plan to preserve him for the playoffs, but he also missed nine consecutive games near the end of the season with a bothersome left hamstring.

Forward Udonis Haslem played in seven games from Jan. 1 until March 1 and didn't play a game in February. But he is now refreshed and back in the rotation.

Forward Michael Beasley has had sporadic minutes this season, including down the stretch when he didn't play in several games and when he did play it usually was less than 10 minutes a game.

Midseason acquisition Toney Douglas has shared time with Mario Chalmers and Norris Cole in the backcourt, and forward Rashard Lewis earned late-season minutes.

"Yes, there's been a lot of fluidity with our lineup," Spoelstra said. "That's either an excuse or something that will make us better. I think it'll make us better. Guys have been able to step up and give us good minutes. We've been able to manage those things without us getting sidetracked."

It hasn't been the perfect season, but Spoelstra said, "You deal with different challenges. We deal with the challenge of trying to conquer success. That's a great place to be in. We'd much rather have that challenge than a different challenge right now."

Spoelstra is a master of at least two things: separating a previous season from the current one and encouraging his players to embrace going outside their comfort zones.

He said once the 2013-14 season started, he didn't talk about last season, the previous season or any other season and he didn't mention trying to win three titles in a row. For the Heat, it's trying to win a title.

Spoelstra thinks that significant improvement is made when players are forced out of their comfort zones and that it pushes them to play in ways they didn't know or think they could, which leads to better basketball.

"I love seeing professionals and a team with a concentrated effort to try and figure it out," Spoelstra said. "Yes, our guys get frustrated and disappointed after the result, but I am not frustrated with us trying to figure it out, because our guys have been completely committed to the process. Once you see that, things tend to work in your way."

This is a very experienced playoff team and has had the ability to find that extra gear in the playoffs. The Heat have been in the most difficult of situations and found their way out multiple times over the last few seasons.

What scenario haven't they seen? Down 3-2 to Boston two seasons ago and won. Down 1-0 to Oklahoma City in the Finals two seasons and won. Down 3-2 to San Antonio last season and trailed 94-89 with 28 seconds left in Game 6 and won the title.

"We're still finding our way, which is tough. â?¦ But I do think our best basketball is ahead of us," Heat forward Shane Battier said. "Ultimately, we're judged on the second season. We all know that. That's been the case since the first year this team was put together.